1. Field of the Invention
The present invention relates generally to centralizer devices used in rock and soil anchoring applications in the construction industry. More particularly, the present invention relates to a novel centralizer device capable of multiple configurations, and capable of manual assembly from component parts, on-site at application construction sites, said assembly requiring no tools.
2. Description of the Related Art
Centralizers are devices used to provide space between an anchorage and the walls of an anchor bore hole, thereby allowing grout to be injected into the bore hole for securing of the anchorage. The centralizer field includes many different inventions which have attempted to improve the functions of the centralizer. Its two primary functions are to: 1) provide space between the anchorage and the walls of the bore hole, and 2) to provide a locking mechanism for the several centralizer elements so that they do not fail once installed in the ground.
More specifically, known relevant prior art has focused on improving the locking mechanism. Unfortunately, patented inventions in this field still exhibit many problems and disadvantages which the present invention has overcome. Even though previous designs have had some success in overcoming past problems, remaining problems include inflexibility in meeting multiple applications, relatively complex locking mechanisms, and using heavy materials such as steel. In addition, known prior art virtually neglects the problem of optimizing the space between the anchorage and the bore hole walls for each application. As is well known in the art, grout is used to secure the anchorage in a bore hole. The more secure the anchorage, the safer the entire anchor, thereby minimizing the possibility of a failure of a dam, a transmission tower, or an oil well, or other anchor applications.
Therefore, it is clear that a need exists for an improved centralizer device that is capable of multiple configurations, capable of being assembled on site, manually requiring no tools, from uniform components, provides an effective mechanism for grout flow, allows use in multiple applications, is light weight, strong, and is even more cost effective to manufacture and ship than existing centralizers. The present invention overcomes these and many other long-standing and even ignored problems and disadvantages of the prior art.
Some of the related prior art includes the following U.S. Patents: Wills, et al. U.S. Pat. No. 4,042,022; Ferstay U.S. Pat. No. 4,866,903; Chickini, Jr. et al. U.S. Pat. No. 4,247,225; Dane U.S. Pat. No. 4,077,470; Wilson U.S. Pat. No. 4,269,269; Spikes U.S. Pat. No. 4,651,823; Patterson et al. U.S. Pat. No. 4,909,322; Svenson U.S. Pat. No. 4,520,869; and Kraft U.S. Pat. No. 4,143,713.
Wills, et al. (U.S. Pat. No. 4,042,022) discloses a centralizer device with a plurality of blades received in slots by a pair of cylindrical collars. This invention is directed towards preventing the separation of parts during use. Disadvantages to this design include the lack of flexibility in the blade material, a design directed to a specific dimension envelope for the centralizer, and an assembly requiring hammers to insert the steel blades, and therefore requiring a lengthy assembly time.
Ferstay (U.S. Pat. No. 4,866,903) discloses a one piece centering device for thread bars. The device has holes to allow grout to pass around or through the device. Disadvantages to this device include restricted applications because of its small size, and lack of an expanding feature to fit different size bore holes. The device seems directed to use only in building applications. Another disadvantage is the small size of the holes in the device to allow grout to pass. It appears that it would be difficult for grout to pass through the small holes in sufficient quantities to provide sufficient force transfer to the ground for a safe anchor. Still another disadvantage is the use with threaded bar. Installing the device takes more time than would an non-threaded device.
Chickini, Jr. et al. (U.S. Pat. No. 4,247,225) discloses an alignment device comprising a single component for mounting an anchor cable in an elongated cable hole in a guy line anchoring environment. One disadvantage with this device is the fixed diameter of the collar for passing cable through. Another disadvantage is the small diameter of the collar for passing any cable through. Still another disadvantage is the somewhat complex locking mechanism to prevent the device from coming apart.
Dane (U.S. Pat. No. 4,077,470) discloses a well centralizer directed to an improved means to connect bow elements to collars. Disadvantages to this device include a complex connecting apparatus, limited applicability in that it is for use only in oil well casings, use of relatively heavy steel for material, and also a need to bend the locking tab to allow for locking the bow elements into the collars.
Wilson (U.S. Pat. No. 4,269,269) discloses a deformable tab on collars as a means to prevent each spring from disengaging from the end collars when the centralizer is subjected to compressional loading. One disadvantage to this device includes limited applicability in that use is only directed to oil, gas, or water drilling situations. Another disadvantage is that the deformable tab does not appear to be of a robust design, therefore the tab is likely to break. Still another disadvantage is that numerous conventional tools, including hammers, vises and pipe wrenches are needed for assembly. Yet another disadvantage is the metal material used requiring forging. The metal material, being relatively heavy compared to plastic, requires more costs for manufacture, crating and shipping.
Spikes (U.S. Pat. No. 4,651,823) discloses a well bore centralizer directed to an improved connectible means between the bowed elements and the collars. Disadvantages include a complex collar locking design, bow elements set to a specific arcuate position, and the hammer force required for assembly. Still another disadvantage is the use of metal in the design, thereby requiring more costs for manufacturing, crating and shipping.
Patterson et al. (U.S. Pat. No. 4,909,322) disclose a casing centralizer with bendable tab to allow a more improved locking mechanism to secure the bow springs in the collars. Disadvantages to this device are similar to others listed in previously mentioned prior art. One disadvantage is the inability of the device to be flexible thereby limiting its applicability to only certain sizes of bore holes. Another disadvantage is the use of metal which increases costs for manufacture, crating and shipping. Yet another disadvantage mentioned in some of the other prior art is the need to bend the metal before the bow springs can be inserted into the collars. Bending the metal can create a point for failure after installation.
Svenson (U.S. Pat. No. 4,520,869) discloses a centralizer for a well casing directed specifically to a third channel of the collar compressible at final assembly allowing for locking of the bow and collar together. Disadvantages in using this device include the complex locking mechanism, limited use to well casings, use of metal requiring more costs, and a need to use hammering tools before assembly can be completed.
Kraft (U.S. Pat. No. 4,143,713) discloses a self-centering basket for use in mining or oil fields. More specifically, the device is directed towards lugs to hold down steel bars to prevent the bars from jumping out of engagement. Disadvantages include the use of steel, thereby increasing manufacturing and shipping costs. Because the design is meant to be locked upon assembly, no means are provided for mistakes in assembly. It would appear to be virtually impossible to disassemble to correct mistakes. In addition, no means are disclosed for altering the outer dimensions of the device should the on site diameter of the bore hole be greater or less than expected.
In summary, all the cited patents have a multitude of disadvantages. As is quickly realized, most of the patents disclose similar attempts to solve one problem with previous centralizer designs. Most are directed to improving centralizer locking techniques. However, problems still exist with attempts to improve centralizer locking techniques. Therefore, it would be highly desirable to solve the locking problem with an elegant, simple, inexpensive centralizer design. In addition, it would be highly desirable to solve other problems in the field of centralizer devices that have been virtually ignored. Therefore, it is an object of the present invention to provide a multiple configuration capable centralizer device allowing hand assembly in the field at construction sites or other sites requiring centralizer applications. Also, the unique features of the present invention allow for its use in virtually any anchoring application situation. It is a further object of the present invention to use a non-metal material, thereby reducing costs throughout the manufacturing to end use process and eliminating the need for any use of conventional tools for assembly. Another object of the invention is to provide numerous interchangeable components for custom orders and multiple embodiments for optimized use in the field, such components allowing for rapid and simple hand assembly requiring no tools, on site, in customer required specifications.
Therefore, the principal object of the present invention is to provide a new and improved centralizer device that is capable of multiple configurations.
It is a further object of the present invention to provide such a new and improved centralizer device that is capable of being assembled on site, manually by hand using no tools, from standardized components.
It is yet a further object of the present invention to provide such a new and improved centralizer device that provides an effective mechanism for grout flow.
It is yet another object of the present invention to provide such a new and improved centralizer device that allows use in multiple applications and is light weight, yet strong. The rigid straps include a central portion semi-circular tapered riser which widens at its peak, and which radius determines the size of rigid strap to use in a given bore hole application, whereby said tapered riser which broadens in the center adds strength to said rigid strap member, and allows for less difficulty in inserting said centralizer system into said bore hole due to increased surface area.
It is yet another object of the present invention to provide such a new and improved centralizer device that is even more cost effective to manufacture and ship to application job sites than existing centralizers.
Briefly, the above and further objects of the present invention are realized by providing a new and improved centralizer device that provides for usage of a number of standardized parts, namely, collars and straps, which may be quickly assembled on-site in the field without the use of tools. These parts are interchangeable to allow for custom configuration of the centralizer device in the field as the circumstances dictate the application requirements.
The parts for the present invention include straps constructed to include three or more separate flexible finger portions, when fully assembled. These flexible finger portions flex toward and snugly fit onto an elongated object to be centrally positioned in a bore hole, and the finger portions allow for the centralizer to be mounted using tie wire or zip tie in grooves on each distal end. This permits the centralizer to be immobilized in position around the object to be centrally positioned in a bore hole. In addition, the collar locking mechanisms located on the straps allows for ease of assembly on location without the use of conventional tools.
The rigid straps include a central portion semi-circular tapered riser which widens at its peak. The radius of the riser determines the size of rigid strap to use in a given bore hole application. The tapered riser which broadens in the center adds strength to the strap and allows for less difficulty in inserting the centralizer system into the bore hole due to increased surface area. The straps include a centrally located gusset on one side, positioned within the curved inner portion to provide strength and reinforcement to the straps.
The straps also include one or more compression tabs on each end for enhanced attachment to an earth anchor rebar, a corrugated pipe or cable strands. The compression tabs are radially cut to provide a tighter conformed attachment to rounded earth anchor mechanisms. In this way, the compression tabs apply direct pressure opposite the tie wire to ensure centralizer movement or slippage is prevented. The rigid strap end consists of flexible fingers which can be compressed to conform to any diameter and can be wired snugly to an object to be centrally positioned.
Another standardized part for the novel centralizer device are two generally cylindrical collars having three or more strap slots which accept the flexible end finger portions of the straps. The individual straps are inserted into each collar manually. Once all straps are inserted in both collars, the centralizer is assembled manually by pushing from both ends, then locked with a unique locking tab mechanism. Therefore, the centralizer can be manually assembled when needed for any given application, and no separate conventional tools are required for centralizer assembly.
While most collars are solid and uniform, having no break or slit, some collars may include one slit to allow for the rapid mounting of the assembled centralizer system onto an elongated object without the need to slide the centralizer system down the length of the elongated object to be centrally positioned in the bore hole. In addition, the collars are constructed so as to provide areas for grout channels between the strap insets.
In a multiple configuration centralizer, a retainer housing having a single slot is used in place of the standardized collars. Each of the straps are manually insertable into the retainer housing slot and locked into place by a locking ramp. A tie retainer clip having a plurality of clip fastening tines each having a raised portion is inserted into the retainer housing slot and is locked into place. The raised portion of the tines locks into the locking ramps within the multiply grooved portion of the strap.
The retainer clip is capable of accepting a zip tie so that the novel multiple configuration centralizer is formed around an elongated object by threading a zip tie through each strap slot formed by the connection of the strap housing and the tie retainer clip. The resulting slot is sized so as to hold the zip tie very snugly, preventing undesired movement when mounting the assembled centralizer system onto an elongated object to be centrally positioned.
The unique locking mechanism includes a locking ramp positioned on an inside surface of the strap when the strap is inserted into the collar slot or the retainer housing slot. The locking ramp prevents movement of the collar along the strap. The straps are constructed with a portion that has a multiple grooves with each groove having a locking tab.
All standardized parts of the novel multiple configuration centralizer are constructed of a thermoplastic material including polypropylene and polyethylene which is easily moldable, provides strength, durability and economy of manufacturing.
The multi-configuration rigid strap centralizer system composed of a plurality of strap housings are fitted with a tie retainer clip and are economically shipped to, and provided on-site in a ladder-like configuration with two zip ties snugly connecting the straps.
Because of the molding process and the materials used for construction of the novel centralizers, costs for manufacturing, crating, and shipping are greatly reduced from the prior art devices. These, and other features and advantages of the present invention are set forth more completely in the accompanying drawings and the following detailed description of the drawings.